Laryngeal Mask Airway

The laryngeal mask airway was invented in 1983 by British anaesthetist, Dr. Archie Brain.The Laryngeal Mask Airway is an alternative airway device used for anesthesia and airway support. It consists of an inflatable silicone mask and rubber connecting tube. It is inserted blindly into the pharynx, forming a low-pressure seal around the laryngeal inlet and permitting gentle positive pressure ventilation. All parts are latex-free.

Use
A laryngeal maskLaryngeal masks are used in anaesthesia and in emergency medicine for airway management. They consist of a tube with an inflatable cuff that is inserted into the pharynx. They cause less pain and coughing than an endotracheal tube, and are much easier to insert. However, a standard laryngeal mask airway does not protect the lungs from aspiration, making them unsuitable for patients at risk for this complication.

The device is useful in situations where a patient is trapped in a sitting position, suspected of trauma to the cervical spine (where tilting the head to maintain an open airway is contraindicated), or when intubation is unsuccessful. It is not inserted as far as an endotracheal tube (it sits tightly over the top of the larynx, and thus does not need to be inserted into the trachea), and supports both spontaneous and artificial ventilation. It is popular in day case surgery.

However, unlike an endotracheal tube, a laryngeal mask cannot protect the airway or lungs from aspiration of regurgitated material, and deep (subglottic) suctioning cannot be performed through the mask. Steps to improve the ability of the laryngeal mask airway (LMA) have included recent improvements such as channels for gastric suction (LMA Proseal, LMA Supreme), and modification to the LMA to allow it to guide endotracheal tubes through its respiratory gas tubing into the larynx, thus protecting the patient against aspiration of gastric contents with the balloon on the end of the endotracheal tube (LMA Fastrack, Cookgas Air-Q)
Guide to use
Laryngeal mask airways come in a variety of sizes ranging from large adult (LMA size 6) to infant (size 0). The LMA functions as a "periphayngeal sealer," in contrast to another category of supraglottic airways which are "base on tongue sealers," such as the Esophageal-Tracheal Combitube and the King Laryngeal tube (LT). A newer generation of the LMA actually utilizes BOTH airway sealing mechanisms (peripharyngeal sealing and base of tongue sealing), and they result in higher average seal pressures during controlled and assisted ventilation of the patient. These models are the LMA Proseal/LMA Supreme and the Cookgas Air-Q.

The cuff of the mask is deflated before insertion and lubricated. The patient is sedated or fully anaesthetized if conscious, and their neck is extended and their mouth opened widely. The apex of the mask, with its open end pointing downwards toward the tongue, is pushed backwards towards the uvula. It follows the natural bend of the oropharynx and comes to rest over the pyriform fossa. Once placed, the cuff around the mask is inflated with air to create a tight seal. Air entry is confirmed by listening for air entry into the lungs with a stethoscope, by presence of end tidal carbon dioxide and by monitoring the degree and pressure at which the air leaks around the mask in the oropharynx.

As with an endotracheal tube, the laryngeal mask airway may be used for procedures in surgical positions other than supine, although anesthetic practice in the United States has largely limited its use to the supine position. European Anesthesiologists report its common use in lateral position and even prone position cases
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